Field of the Invention
The present invention relates to a fuel cell, a fluid distribution device for a fuel cell, and a vehicle with a fuel cell. More specifically, the present invention relates to a compact, high-output fuel cell, a fluid distribution device thereof, and a vehicle with a fuel cell.
Background Information
A fuel cell is a type of power generating device for extracting electricity by electrochemically oxidizing fuels such as hydrogen and methanol, which has been drawing attention as a clean energy source in recent years. Fuel cells are classified into phosphoric acid types, molten carbonate types, solid oxide types, polymer electrolyte types, etc., according to the type of electrolyte used.
Of these, a polymer electrolyte fuel cell (PEFC) comprises a membrane electrode assembly (MEA) in which electrodes are disposed on both surfaces of an electrolyte membrane. Power is then generated by supplying hydrogen (fuel gas) on one surface and oxygen (oxidation gas) on the other surface of the membrane electrode assembly. Since a volumetric output density equivalent to an internal combustion engine can be obtained with such a PEFC, research is being advanced on the practical applications thereof as a power source for electric vehicles, etc. (refer to, for example, Patent Documents 1 and 2).
Various types of packaging methods for the membrane electrode assembly have been proposed, such as the stacked type, the pleated type, and the hollow fiber type. Of these, stacked fuel cells, which are configured by stacking sheet-shaped membrane electrode assemblies with sheet-shaped separators in between, are being widely used.
The output of a fuel cell is proportional to the membrane area and is not proportional to the fuel cell volume. Accordingly, reducing the cell pitch is effective at achieving miniaturization and high output in a stacked fuel cell. However, if only the cell pitch is reduced, pressure loss becomes excessive when fluids such as air, hydrogen, and cooling water pass through the inner surface of the cells. The result of excessive pressure loss is contrary to the demand for a reduction in auxiliary power and, thus, is not preferable.
Accordingly, the present inventors have proposed a fuel cell comprising a low-aspect structure in which the length in the width direction perpendicular to the flow channel direction is longer than the length in the flow channel direction of an approximately rectangular fuels cell (refer to WO 2011/059087).
Fluid that is supplied to a fuel cell is supplied via various fluid machinery, such as a compressor, an ejector, a floor, and a pump, as well as via additional piping. For example, in a fuel cell used for automobiles, each fluid is supplied via pipes having a diameter of about 50 mm. Accordingly, when the length in the width direction is significantly wider, when compared to the sizes (diameters) of such pipes, evenly supplying the fluid across the entire width direction becomes difficult. Therefore, a fuel cell having a low-aspect structure requires a fluid distribution mechanism for expanding the size of fluid flow from the size (diameter) of the pipes to the size of the low-aspect structure fuel cell in the width direction. However, a conventional fluid distribution mechanism configured by combining a plurality of pipes is large and bulky; as a result, there is the problem that miniaturization of the fuel cell as a whole is inhibited. See also, Japanese Laid-Open Patent Application No. 2005-190946 JP and Japanese Laid-Open Patent Application No. 2007-287659 JP.